Ground positioning system applied in a distance measuring device

ABSTRACT

A ground positioning system integrated with a distance measuring device that detects the distance from the device to a selected object for each pixel of the captured image of the selected object. The system, which also includes an azimuth sensor, calculates ground positioning coordinates of a selected object that correspond to a certain pixel of captured image using distance information, device ground positioning coordinates and device direction information.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a distance measuring device by which athree-dimensional shape of a measurement subject, which is to bemeasured, is captured by a time-of-flight measurement.

2. Description of the Related Art

Conventionally, a distance measuring device that detects distance fromthe device to a measurement subject for each pixel of an imaging deviceis known in “Measurement Science and Technology” (S. Christie et al.,vol. 6, p.1301-1308, 1995) or International Publication No. WO97/01111.The above distance measuring device radiates pulse modulated laser lightbeams to the measurement subject and receives the reflected light beamson the imaging device, a two-dimensional CCD sensor, and the receivedlight beams are converted to electric signals at each of thephotoelectric conversion elements of the CCD. The shuttering operationof the distance measuring device is so controlled as to correlateelectric signals, which are detected at each of the photo-diodes, withdistance information from the device to the measurement subject. Fromthe electric signals, the distance information from the device to themeasurement subject is detected at each pixel of the CCD, and thethree-dimensional distance information that indicates the topography ofthe measurement subject is obtained. However, the three-dimensionaldistance information of the measurement subject is comprised only ofrelative distances from the device and the ground position of themeasurement subject is not obtainable.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a ground positioningsystem, which detects the ground position of a measurement subject,applied in the distance measuring device that detects the distance fromthe device to a measurement subject for each pixel of the captured imageof the measurement subject.

According to the present invention, there is provided a groundpositioning system applied in a distance measuring device that detectsthe distance from the distance measuring device to a measurement subjectfor each pixel of the captured image of the measurement subject. Theground positioning system comprises a ground position detectingprocessor, an azimuth detecting processor and a subject positioncalculating processor.

The ground position detecting processor detects the ground positioningcoordinates of the distance measuring device. The azimuth detectingprocessor detects the direction of the distance measuring device. Thesubject position calculating processor calculates the ground positioningcoordinates of a subject that correspond to a certain pixel of capturedimage using the distance value, the ground positioning coordinates andthe direction of the distance measuring device.

Preferably, the ground positioning system further comprises an imageindicating processor, an input processor, a map information searchprocessor and a superimpose processor. The image indicating processordisplays the captured image on a screen. The input processor is forselecting at least one pixel of the image, which is indicated on thescreen by the image indicating processor. The map information searchprocessor searches a piece of map information that corresponds to theground positioning coordinates of a pixel which is selected by the inputprocessor. The superimpose processor superimposes the piece of mapinformation, which is searched by the map information search processor,in proximity to the selected pixel.

In a preferable example of the ground positioning system, the inputprocessor may comprise a touch screen, the map information may comprisenames of facilities that exist at locations indicated with the groundpositioning coordinates and the ground positioning coordinates maycomprise longitude and latitude.

Further, the preferred example of the ground positioning systemcomprises an inclination detecting processor that detects theinclination angle of the distance measuring device. The positioncalculating processor calculates the ground positioning coordinates ofthe subject. The coordinates corresponds to the distance value, thatcoincides with a certain pixel of the captured image, and the groundpositioning coordinates, the direction and inclination angle of thedistance measuring device.

The ground position detecting processor comprises a GPS (GlobalPositioning System) receiver so as to detect the ground positioningcoordinates.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the present invention will be betterunderstood from the following description, with reference to theaccompanying drawings in which:

FIG. 1 is a perspective view showing a camera provided with a distancemeasuring device of the present embodiment of the present invention;

FIG. 2 is a block diagram showing an electrical construction of thecamera of the present embodiment;

FIG. 3 is a view showing the principle behind the distance measurement;

FIG. 4 is a timing chart showing a distance measuring light beam, areflected light beam, a gate pulse and a distribution of an amount of alight beam received by a CCD;

FIG. 5 is a plan view showing the disposition of photo-diodes and avertical transfer unit, which are provided in the CCD of the presentembodiment;

FIG. 6 is a sectioned elevational view of the CCD;

FIG. 7 is a timing chart of a distance information sensing operation bywhich data, corresponding to a distance from a camera body to each pointon the surface of a measurement subject, is sensed in the presentembodiment;

FIG. 8 shows the flowchart of the distance information sensing operationof the present embodiment;

FIG. 9 shows the flowchart of the program executed in the playback mode;

FIG. 10 illustrates a disposition of the image indicating LCD panel, theREC/PLAY mode switch on the backside of the camera body and an exampleof a display on the LCD;

FIG. 11 indicates a disposition of a selected pixel in the CCD;

FIG. 12 illustrates the relation between the angle of view and theimaging surface of the CCD;

FIG. 13 shows a disposition of the optical axis and the selectedsubject, with two-dimensional Cartesian coordinates in the horizontalplane, and the coordinate system whose origin is identical to the camerabody; and

FIG. 14 illustrates a three-dimensional disposition of the optical axisand the selected subject with Cartesian coordinates with the origin ofthe axes at the camera.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described below with reference to embodimentsshown in the drawings.

FIG. 1 is an external view of a camera type distance measuring device ofa first embodiment of the present invention.

On a front surface of a camera body 10, a view-finder window 12 isprovided toward the left-upper edge, adjacent to a photographing lens11, and an electronic flash 13 is disposed toward the right-upper edge.On the upper surface of the camera body 10, a light emitting device 14,which radiates a laser beam is, mounted above the photographing lens 11.A release switch 15 and a liquid crystal display panel 16 are providedon the left side of the light emitting device 14 and a mode change dial17 is provided on the right side of the device 14. On a side surface ofthe camera body 10, a card slot 19 is formed, into which a recordingmedium, such as an IC memory card, is insertable, and a video outputterminal 20, an interface connector 21 and a connector 18 for a GPS(global positioning system) antenna are also provided. Further, on thebackside of the camera body 10, an image indicating LCD panel 37 and aREC/PLAY mode switch 29, which alternatively selects a recording mode orplayback mode (refer FIG. 10), are disposed.

FIG. 2 is a block diagram showing an electrical construction of thecamera of FIG. 1.

An aperture 25 is provided in the photographing lens 11. The openingdegree of the aperture 25 is adjusted by an iris drive circuit 26. Afocusing operation and a zoom operation of the photographing lens 11 arecontrolled by a lens drive circuit 27.

An imaging device (CCD) 28 is disposed on an optical axis of thephotographing lens 11. A subject image is formed on the light receivingsurface of the CCD 28 through the photographing lens 11, and an electriccharge corresponding to the subject image is generated therein. Anoperation, such as an accumulating operation and a reading operation ofthe electric charge of the CCD 28, is controlled by a CCD drive circuit30. An electric charge signal, i.e., an image signal, read from the CCD29 is amplified by an amplifier 31, and is converted from an analogsignal to a digital signal by an A/D converter 32. The digital imagesignal is subjected to a process, such as gamma correction, in the imagesignal process circuit 33, and is stored as digital image data in animage memory 34. The iris drive circuit 26, the lens drive circuit 27,the CCD drive circuit 30 and the image signal process circuit 33 arecontrolled by a system control circuit 35.

The digital image data are read from the image memory 34 and supplied toan LCD drive circuit 36, which is operated in accordance with thedigital image data, so that an image corresponding to the digital imagedata is displayed on an image indicating LCD panel 37.

The digital image data read from the image memory 34 is also transmittedto a TV signal encoder 38, so that the digital image data can betransmitted to a peripheral monitor device 39, provided externally tothe camera body 10, through the video output terminal 20. The systemcontrol circuit 35 is connected to an interface connector 21 via aninterface circuit 40. Therefore, the digital image data read from theimage memory 34 can also be transmitted to a computer 41 connected tothe interface connector 21 via an interface cable. Further, the systemcontrol circuit 35 is connected to an image recording device 43 througha recording medium control circuit 42. Therefore, the digital image dataread from the image memory 34 can be recorded in a recording medium M,such as an IC memory card, mounted in the image recording device 43.

A light emitting element control circuit 44 is connected to the systemcontrol circuit 35. The light emitting device 14 is provided with alight emitting element, such as laser diode (LD) 14 a, and anillumination lens 14 b. The operation of the light emitting element 14 ais controlled by the light emitting element control circuit 44. Thelight emitting element 14 a radiates a laser beam as a distancemeasuring light beam. The laser beam irradiates the whole of ameasurement subject through the illumination lens 14 b. The laser beamreflected by the measurement subject becomes incident on thephotographing lens 11. By detecting the reflected laser beam with theCCD 28, information relating to the distance from the camera to themeasurement subject is sensed at each pixel of the CCD 28.

The GPS antenna 50 is connected with the GPS receiver 22 through theconnector 18 and the GPS receiver 22 is connected to the system controlcircuit 35. It can detect the longitude, latitude and altitude of thecamera by receiving signals from satellites of the Global PositioningSystem (GPS) and send them to the system control circuit 35. Further, anazimuth sensor 46 and an inclinometer 48 are provided in the camera. Thedirection of the optical axis of the photographing lens 11 and angles ofinclination of the camera body 10 are respectively obtained from theazimuth sensor 46 by an azimuth sensing control circuit 47 and from theinclinometer 48 by an inclinometer control circuit 49. The azimuthsensing control circuit 47 and the inclinometer control circuit 49 areconnected to the system control circuit 35, and the direction and theangles of inclination are sent to the system control circuit 35.

A superimpose circuit 24 is connected to the LCD drive circuit 36, theTV signal encoder 38 and the system control circuit 35. The superimposecircuit 24 superimposes text information onto an image displayed on theimage indicating LCD panel 37 or monitor 39. The superimposed textrelates to the map information and is stored in a memory 41M of thecomputer 41. A piece of information, which is superimposed on the imagedisplayed on the image indicating LCD panel 37, is read from the memory41M and sent to the system control circuit 35 via the interface circuit40.

The liquid crystal display panel 16, a touch screen 23 and a switchgroup 45, including the release switch 15, the mode change dial 17 andthe REC/PLAY mode switch 29 are connected to the system control circuit35. Note that the touch screen 23 is a transparent filmy cover placedover the screen of the LCD panel 37.

With reference to FIGS. 3 and 4, the principle behind the distancemeasurement in the embodiment is described below. Note, in FIG. 4, theabscissa indicates time “t”.

A distance measuring light beam output by a distance measurement deviceB is reflected by the measurement subject S, and the reflected lightbeam is sensed by a CCD (not shown). The distance measuring light beamis a pulse, the width of which is “H”. Accordingly, the reflected lightbeam is a pulse, the width of which is “H”, similarly to the distancemeasuring light beam. Therefore, a rise of the pulse of the reflectedlight beam occurs after a rise of the pulse of the distance measuringlight beam by time δ·t (δ is a delay coefficient). Since the distancemeasuring light beam and the reflected light beam have both traveled adistance “r” between the distance measurement device B and the measuredsubject S, the distance “r” is represented as follows:

r=δ·t·C/2  (1)

wherein “C” is the speed of light.

For example, by setting a condition in such a manner that the reflectedlight beam can only be sensed from a rise of the pulse of the distancemeasuring light beam to a point prior to a fall of the pulse of thereflected light beam, i.e., by providing a gate pulse corresponding to areflected light beam detecting period T, an amount “A” of received lightfrom the reflected light beam becomes a function of the distance “r”.Namely, the greater the distance “r” (or the greater the time δ·t), theless the received light amount A.

In the embodiment, by taking advantage of the principle described above,the received light amount A is sensed using each of the photo-diodes ofthe CCD 28, the distance from the camera body 10 to each point on thesurface of the measurement subject S is sensed, and data relating to thethree-dimensional image, which indicates the topography of themeasurement subject S, can be obtained.

FIG. 5 is a plan view showing the disposition of the photo-diodes 51 anda vertical transfer unit 52, which are provided in the CCD 28. Inpractice a multitude of photo-diodes 51 are arranged in a matrix and acorresponding vertical transfer unit 52 is disposed beside each verticalcolumn of photo-diodes 51. FIG. 6 is a sectioned elevational view of theCCD 28 in which the CCD 28 is cut by a plane perpendicular to asubstrate 53. The CCD 28 is an interline CCD of vertical overflow drain(VOD) type, in which unwanted charge is discharged to the substrate 53.

The photo-diodes 51 and the vertical transfer unit 52 are formed along asurface of the n-type substrate 53. A plurality of photo-diodes 51 aretwo-dimensionally disposed in a matrix arrangement, and the verticaltransfer unit 52 is disposed adjacent to the photo-diodes 51, parallelto rows extending in a vertical direction in FIG. 5. The verticaltransfer unit 52 has four vertical transfer electrodes 52 a, 52 b, 52 cand 52 d, which correspond to each of the photo-diodes 51. Therefore, inthe vertical transfer unit 52, four potential wells can be formed, sothat a signal charge is output from the CCD 28 by controlling a depth ofthe wells, as is well known. Note that the number of the verticaltransfer electrodes can be changed, depending upon the requirement ofthe CCD 28.

The photo-diodes (PD) 51 and the vertical transfer unit (V-CCD beingsignal charge holding unit) 52 are disposed in a p-type well formed on asurface of the substrate 53. The p-type well is completely depleted dueto an inverse bias voltage applied between the p-type well and then-type substrate 53. In this state, electric charge is accumulated inthe photo-diodes 51, and an amount of the electric charge corresponds toan amount of an incident light beam, which is the reflected light beamreflected by the measurement subject. When a substrate voltage ischanged to a value greater than a predetermined value, electric chargeaccumulated in the photo-diodes 51 is discharged to the substrate 53.Conversely, when an electric charge transfer signal, which is a voltagesignal, is applied to a transfer gate (TG) 54, the electric chargeaccumulated in the photo-diodes 51 is transferred to the verticaltransfer unit 52. Namely, after the electric charge is discharged to thesubstrate 53 by the electric charge discharging signal, the signalcharge accumulated in the photo-diode 51 is transferred to the verticaltransfer unit 52 by the electric charge transfer signal. By repeatingthe discharge and the transfer, an electronic shuttering operation isperformed.

FIG. 7 is a timing chart of a distance information sensing operation bywhich data, corresponding to the distance from the camera body 10 toeach point on a surface of the measurement subject, is sensed. Thedistance information sensing operation is described below with referenceto FIGS. 1, 2, 5, 6 and 7. Note that the timing chart of the distanceinformation sensing operation in the present embodiment is slightlydifferent from the timing chart of the distance measurement principle,which was described above with reference to FIG. 4. Namely, the timingchart of the present embodiment is set so as to sense the reflectedlight beam from a point subsequent to the rise of the reflected lightbeam pulse to a point subsequent to the fall. By this manner, the noisecomponent due to ambient daylight may be reduced, though the principlesof the above distance measurement means are basically the same.

In synchronization with an output of a vertical synchronizing signal(not shown), an electric charge discharging signal (a pulse signal) S1is output, so that unwanted charge, which is accumulated in thephoto-diodes 51, is discharged to the substrate 53. The electric chargevalue, while the pulse signal S1 is output, is indicated as S2 in thechart. After the electric charge discharging signal S1 is output, thelight emitting device 14 is actuated, and thus a distance measuringlight beam S3, which is a pulsed beam having a constant width T_(S), isoutput therefrom. A period for outputting the distance measuring lightbeam S3 or the width of the pulse beam is modulated according to arequirement. In the present embodiment, the distance measuring lightbeam S3 is modulated to be completed approximately simultaneously withcompletion of the output of the electric charge discharging signal S1.

The distance measuring light beam S3 is reflected by the measurementsubject, and enters the CCD 28 as a reflected light beam S4. When theoutput of the electric charge discharging signal S1 ends, the electriccharge for incident light, which comprises the reflected light beam S4and ambient daylight, starts on each of the photo-diodes and a signalcharge S5 is sensed. When an incident of the reflected light beam S4 iscompleted, i.e. after the fall indicated by the reference sign S6, thephoto-diodes only generate signal charge S8 due to ambient daylight.

Then an electric charge transfer signal S9 is output to the verticaltransfer electrodes 52 a, and an electric charge accumulated in thephoto-diodes 51 is transferred to the vertical transfer unit 52. Theoperation of transferring the accumulated electric charge in thephoto-diodes 51 ends with the fall S10, which is a termination of theoutput of the electric charge transfer signal S9. Namely, a signalcharge S11 of which electric signal accumulation was started just afterthe completion of the electric charge discharging signal output andterminated just after the completion of the output of the electrictransfer signal S9, is transferred to the vertical transfer unit 52,while the photo-diodes continue to accumulate electric signals S14 dueto ambient daylight.

Thus during a period T_(U1) from the end of the output of the electriccharge discharging signal S1 to the end of the output of the electriccharge transfer signal S9, a signal charge S11, corresponding todistances from the camera body 10 to the measurement subject and theambient daylight is accumulated in the photo-diodes 51. Namely, thesignal charge S12, a hatched portion of signal charge S11, correspondsto the distances from the camera body 10 to the measurement subject,while a residual portion S13 of the signal charge S11 is the result ofambient daylight.

When a predetermined time has elapsed since the output of the electriccharge transfer signal S9, a subsequent electric charge discharge signalis output, so that the signal charge S14, an electric charge accumulatedin the photo-diodes after the signal charge transfer to the verticaltransfer unit 52, is discharged to the substrate 53. Subsequently,another signal charge is accumulated in the photo-diodes 51. Then,similarly to the above description, when the electric chargeaccumulation period T_(U1) has again elapsed, the signal charge S11 istransferred to the vertical transfer unit 52.

The transferring operation of the signal charge S11 to the verticaltransfer unit 52 is repeatedly performed until the next verticalsynchronizing signal (not shown) is output. Thus, the signal charge S11is integrated in the vertical transfer unit 52. The signal charge S11integrated for one field period, which is between two verticalsynchronizing signals, corresponds to distance information of themeasurement subject, on condition that the measurement subject isstationary for the period between the two vertical synchronizingsignals. Note that an amount of the signal charge S13 is small enough tobe omitted when it is compared with that of the signal charge S12, thusthe signal charge S11 can be regard as the signal charge S12.

The detecting operation of the signal charge S11 described above iscarried out in all of the photo-diodes 51 provided in the CCD 28. As aresult of the detecting operation for one field period, the distanceinformation sensed by the photo-diodes 51 is held in each correspondingvertical transfer unit 52, which is located adjacent to each column ofphoto-diodes 51. The distance information is output from the CCD 28 by avertical transferring operation of the vertical transfer units 52 and ahorizontal transferring operation of a horizontal transfer unit (notshown).

Next, the distance information sensing operation in the presentembodiment is explained with reference to FIG. 8, which describes a flowchart of the operation. Note that, the distance information sensingoperation is executed in the recording mode, which is set by theREC/PLAY mode switch 29.

When it is recognized in Step 101 that the release switch 15 is fullydepressed, Step 102 is executed in which the vertical synchronizingsignal is output and a distance measuring light beam control is started.Namely, the light emitting device 14 is driven so that the distancemeasuring light beam S3 is intermittently output as a pulsed beam. Then,Step 103 is executed so that a sensing operation control of the CCD 28is started. Namely, the distance information sensing operation describedwith reference to FIG. 7 is started, and thus the electric chargedischarging signal S1 and the electric charge transfer signal S9 arealternately output, so that the signal charge S11 of the distanceinformation is integrated in the vertical transfer unit 52.

In Step 104, it is determined whether one field period has elapsed sincethe beginning of the distance information sensing operation, i.e.,whether a new vertical synchronizing signal has been output. When onefield period has passed, the process goes to Step 105 in which thesignal charge S11 of the distance information is output from the CCD 28.The signal charge S11 is then temporarily stored in the image memory 34in Step 106.

In Step 107, the distance measuring light beam control is turned OFF,and thus the light emitting operation of the light emitting device 14 isterminated. In Step 108, a calculation process of the distancemeasurement (D) data is performed by using the distance information.Then the D data is output and temporarily stored in the image memory 34in Step 109.

In Step 110, a normal photographing operation (i.e., CCD video control)is turned ON. The image of the measurement subject, which corresponds tothe distance information, is then sensed as image data. The image datais temporarily stored in the image memory 34 at Step 111.

In Step 112, the direction of the optical axis of the photographing lens11 is detected with the azimuth sensor 46, and in Step 113, theinclination of the camera body 10 is sensed by the inclinometer 48. Instep 114, the ground position of the camera, which is indicated with thelongitude, latitude and altitude of the camera, is obtained. The groundpositioning coordinate, such as the longitude, latitude and altitude areanalyzed from the signals, which are transmitted from the satellites forthe global positioning system (GPS) and received by the GPS antenna. InStep 115, the distance measurement data and the image data, whichrespectively stored in the image memory 34 in Step 109 and Step 111, arerecorded in the recording medium M as a single file with data indicatingthe direction, the inclination and the ground positioning coordinates(longitude, latitude, altitude) of the camera. This distance informationsensing operation then ends.

Next, with reference to FIG. 7, the calculation executed in Step 108 isdescribed.

It is supposed that the measurement subject of reflectance R isilluminated and an image of the measurement subject is formed on the CCD28 while regarding the measurement subject to be a secondary lightsource. At this time, an output Sn, which is obtained by integrating anelectric charge generated in a photo-diode for an electric chargeaccumulation period “t”, is indicated as follows:

 Sn=k·R·I·t  (2)

wherein “k” is a proportional coefficient, which is varied in accordancewith an F-number and a magnification of the photographing lens. “I” is aluminance of the measurement subject while regarding the subject as asecondary light source.

As shown in FIG. 7, it is supposed that the electric charge accumulationperiod is T_(U1), the pulse width of the distance measuring light beamS3 is T_(S), a pulse width of the signal charge S12 of the distanceinformation is T_(D), and the electric charge accumulation period isrepeated N times (a predetermined number of times) for one field period.An output SM₁₀ of the CCD is: $\begin{matrix}\begin{matrix}{{SM}_{10} = {\sum{k \cdot R \cdot I \cdot T_{D}}}} \\{{= {k \cdot N \cdot R \cdot I \cdot T_{D}}},}\end{matrix} & (3)\end{matrix}$

wherein the pulse width T_(D) is indicated as follows: $\begin{matrix}\begin{matrix}{T_{D} = {\delta \cdot t}} \\{= {2{r/{C.}}}}\end{matrix} & (4)\end{matrix}$

Therefore, the distance r, which is from the camera to the measurementsubject, is described in the following form:

r=C·SM ₁₀/(2·k·N·R·I)  (5)

FIG. 9 describes a flow chart of a process executed in the camera whenthe REC/PLAY mode switch is set to the playback or PLAY mode, in whichthe photographed still video image of the measurement subject isdisplayed on the image indicating LCD panel 37 and the groundpositioning coordinates of the measurement subject are detected.

When it is determined that the REC/PLAY mode switch is set to theplayback or PLAY mode, in Step 201, the process succeed to Step 202. InStep 202, the still video image data stored in the recording medium M inStep 115 of FIG. 8 is read and displayed on the image indicating LCDpanel 37.

In Step 203, it is determined whether an input signal from the touchscreen 23 for indicating and selecting a particular subject in thedisplayed image exists. If it is determined that there is no inputsignal from the touch screen 23, Step 207 determines whether theREC/PLAY mode switch is switched to the recording mode and the playbackmode is canceled. If the mode is still set to playback mode, the processreturns to Step 203 and this cycle continues until an input signal fromthe touch screen 23 is input or the REC/PLAY mode switch is switched tothe recording mode. When it is determined that the REC/PLAY mode switchis switched to the recording mode and the playback mode is canceled inStep 207, this routine ends.

The surface of the image indicating LCD panel 37 is overlaid with thefilmy touch screen 23. When a certain position of the screencorresponding to a particular point or part of the image is touched by afinger or pointed with a pointing pen, as shown in FIG. 10, the abovetouched or pointed position of the touch screen is detected andcorresponding address of the screen is obtained. When a particularsubject is indicated with the finger or with the pointing pen, and asignal from the touch screen is input in Step 203, then the processsucceed to Step 204. Note that FIG. 10 illustrates the image indicatingLCD panel 37 and the REC/PLAY mode switch 29 provided on the backsidesurface of the camera body 10.

In Step 204, the pixel corresponding to the above address of the touchscreen is obtained. Then the average of distance data is calculated forpixels within a certain proximity to the pixel. The average of thedistance data is regarded as distance information D that represents adistance for a selected subject, which is indicated by a finger or witha pointing pen.

In Step 205, the ground position of the selected subject or the absoluteposition of the selected subject on the map is obtained from thedistance information D, the ground positioning coordinates, thedirection data and inclination data, which are respectively detected inStep 112 and 113 of FIG. 8. Then locational information for the selectedsubject is searched for and read out from the map data stored in thememory 41M of the computer 41 (see FIG. 2), with reference to the groundposition coordinates of the selected subject. Additional locationalinformation may be the name or address of the facilities, and so on,which exist at the position indicated by the above ground positioningcoordinates. Namely, a user may know the name or the address of thefacilities by selecting a particular subject on the screen. In Step 206,the locational information of the selected subject is superimposed onthe image of the measurement subject displayed on the image indicatingLCD panel 37, and it is displayed adjacent to the selected subject. Thenthe process returns to Step 202, and repeatedly executed until theREC/PLAY mode switch is switched to the recording (REC) mode.

FIG. 11 through FIG. 14, refer to the explanation of the calculationexecuted in Step 205 so as to obtain the ground position of the selectedsubject are explained.

FIG. 11 is a front view of the CCD 28. The width of the CCD 28 is 2×W₀and the point P represents a pixel transversely apart from the center ofthe imaging surface of the CCD 28, at a distance of W_(P). FIG. 12 showsthe disposition of the imaging surface of the CCD 28 and the focal pointP_(f), where f and θ₀ represent the focal length and the angle of viewrespectively. The line segment PP_(f), which is between the point P andthe focal point P_(f), is at an angle of θ_(P) with the optical axisL_(P) of the camera. The angle of view θ₀ and the angle θ_(P) are thendescribed as follows:

θ₀=2×tan⁻¹(W ₀ /f)  (6)

 θ_(P)=tan⁻¹(W _(P) /f).  (7)

FIG. 13 illustrates the position of the subject S_(P), which correspondsto the pixel at the point P of the CCD 28, in the horizontal plane. Theorigin O of the coordinate system O-XY is taken at the focal pointP_(f), the X-axis is directed to the east direction and Y-axis to thenorth direction. The half line (broken line) L_(P) is the optical axisof the camera and is identical to the direction of camera. Thecoordinates (Δx, Δy) of the subject S_(P), in the O-XY coordinatessystem, is described in the following:

Δx=D _(P)×sin(θ_(n)+θ_(P)),  (8)

Δy=D _(P)×cos(θ_(n)+θ_(P)).  (9)

Where θ_(n) represents an angle between the optical axis L_(P) and the Yaxis, and D_(P) represents a distance from the focal point to thesubject S_(P), which corresponds to the pixel at the point P of the CCD28. Note that the distance D_(P) corresponds to the distance informationD, which indicates an average of distance data around the pixel at P.

When the longitude and the latitude of the camera (or the origin O)obtained by the GPS are φ and ψ, the coordinates of the subject S_(P),which are respectively represented by φ_(P) and ψ_(P), are calculatedwith

φ_(P) =φ+α·Δx,  (10)

ψ_(P) =ψ+β·Δy,  (11)

where, α and β are coefficients, at (φ, ψ) , for transforming distancesin X and Y direction to angles of the longitude and the latituderespectively.

Therefore, with reference to the equations (7) through (11), thelongitude φ_(P) and the latitude ψ_(P) of the subject S_(P) are obtainedby the following form:

φ_(P) =φ+α·D _(P)·sin(θ_(n)+tan⁻¹(W _(P) /f)),  (12)

ψ_(P) =ψ+β·D _(P)·cos(θ_(n)+tan⁻¹(W _(P) /f))  (13)

Next, with reference to FIG. 14, the method of calculating the longitudeand the latitude of the subject S_(P), that is the coordinates (φ_(P)′,ψ_(P)′) for the inclined camera, is explained.

FIG. 14 schematically illustrates a three dimensional disposition of thesubject S_(P) corresponding to the pixel at the point P of the CCD 28and the focal point or the origin O of the coordinate system O-XYZ. TheX-axis is directed to the east and the Y-axis to the north. Further, theZ-axis is directed to the vertical direction. The line segment (brokenline) L_(P) indicates the direction of the camera and is identical tothe optical axis of the camera. The point S_(P)′ is the projection ofthe subject S_(P) on the XY plane, which is a horizontal plane. The lineL_(P)′ is the projection of the optical axis L_(P) on the XY plane. Thedistance D_(P) corresponds to the length, of the segment OS_(P), andD_(P)′ corresponds to the length of the segment OS_(P)′, which is theprojection of the segment OS_(P) on the XY plane. The angle θ_(Z)indicates the angle between the segment line OS_(P) and the segment lineOS_(P)′. In this example, the angle is identical to the angle of theoptical axis L_(P) to the XY plane or the horizontal plane; namely, itindicates inclination or inclined angle of the camera body 10. The angleθ_(P) is an angle between the segment line L_(P)′ and the segment lineOS_(P)′, and the angle θ_(n)′ is an angle between the segment lineL_(P)′ and the Y-axis.

The coordinates (φ_(P)′, ψ_(P)′) of the subject S_(P), which correspondsto the point P, is derived by substituting D_(P)′ to D_(P) and θ_(n)′ toθ_(n) of the equation (12) and (13). With the substitution, the equation(12) and (13) yield to

φ_(P) ′=φ+α·D _(P)′·sin(θ_(n)′+tan⁻¹(W _(P) /f)),  (14)

ψ_(P) ′=ψ+β·D _(P)′·cos(θ_(n)′+tan⁻¹(W _(P) /f)),  (15)

where D_(P)′ is

D _(P) ′=D _(P)×cos θ_(Z).  (16)

Thus, the coordinates (φ_(P)′, ψ_(P)′) are calculated by the followingform:

φ_(P) ′=φ+α×D _(P)×cos θ_(Z) ×sin(θ_(n)′+tan⁻¹(W _(P) /f)),  (14)

ψ_(P) ′=ψ+β·×D _(P)×cos θ_(Z)×cos(θ_(n)′+tan⁻¹(W _(P) /f))  (15)

As described above, according to the present embodiment, the longitudeand latitude of a selected subject in a captured image is obtainable.Further, when applying the map data, a database of related or locationalinformation, such as the name and/or address, and so on, of the facilitycorresponding to the above selected subject is also accessible and maybe displayed on the screen.

In the present embodiment, the camera refers to the map data stored inthe memory 41M of the computer 41 and it is transferred through theinterface cable connected between the camera and the computer 41.However, the map data may be stored in a memory provided in the cameraor in the recording medium M. Further, the image data, distance data,direction data, ground positioning coordinate data and the inclinationdata may be transferred to the computer 41 so that the selection of thesubject is carried out using the image on the display of the computer 41and selecting the subject with the mouse pointer. The locationalinformation of the selected subject may also be displayed on thecomputer display.

In the present embodiment, the GPS antenna 50 is described as aperipheral device and connected to the camera body 10 with a cable. Itmay also be installed inside the camera body 10.

Although the embodiments of the present invention have been describedherein with reference to the accompanying drawings, obviously manymodifications and changes may be made by those skilled in this artwithout departing from the scope of the invention.

The present disclosure relates to subject matter contained in JapanesePatent Application No. 11-272532 (filed on Sep. 27, 1999) which isexpressly incorporated herein, by reference, in their entireties.

What is claimed is:
 1. A ground positioning system applied in a distancemeasuring device that detects distances from said distance measuringdevice to a measurement subject for each pixel of a captured image ofsaid measurement subject, and said ground positioning system comprising:a ground position detecting processor that detects the groundpositioning coordinates of said distance measuring device; an azimuthdetecting processor that detects the direction of said distancemeasuring device; and a subject position calculating processor thatcalculates the ground positioning coordinates of a subject thatcorresponds to a certain pixel of said captured image from saiddistance, said ground positioning coordinates of said distance measuringdevice, and said direction.
 2. A system according to claim 1,comprising: an image indicating processor that indicates said image on ascreen; an input processor for selecting at least one pixel of saidimage, which is indicated on said screen by said image indicatingprocessor; a map information search processor that searches a piece ofmap information that corresponds to said ground positioning coordinatesof a selected pixel, which is selected by said input processor; and asuperimpose processor that superimposes a piece of said map information,which is searched by said map information search processor, in proximityto said selected pixel.
 3. A system according to claim 2, wherein saidinput processor comprises a touch screen.
 4. A system according to claim2, wherein said map information comprises names of facilities that existat locations indicated with said ground positioning coordinates.
 5. Asystem according to claim 1, wherein said ground positioning coordinatescomprise longitude and latitude.
 6. A system according to claim 1,comprising an inclination detecting processor that detects aninclination angle of said distance measuring device, and wherein saidposition calculating processor calculates said ground positioningcoordinates of said subject, which corresponds to a certain pixel ofsaid captured image, from said distances that correspond to said certainpixel of said captured image, said ground positioning coordinates ofsaid distance measuring device, said direction and said inclinationangle of said distance measuring device.
 7. A system according to claim1, wherein said ground position detecting processor comprising a GPS(Global Positioning System) receiver so as to detect said groundpositioning coordinates.